TabLayout 和 WebView

Question

我想制作一个基于 WebView 的带有标签的应用程序。我的问题是：是否可以将片段用作 webview 并根据我按下的选项卡设置 url？例如，如果我按第一个选项卡转到https://www.google.com，按第二个选项卡转到https://www.facebook.com（我不想为每个网址制作一个特定的片段）。 如果是，谁能解释我怎么做？

如果没有，android 有另一个库可以制作我想要的东西吗？ （我试图避免Bottomnavigationview，因为与徽章通知不兼容，我也试图避免第三方库）。

谢谢！

-- 编辑

public class MainActivity extends AppCompatActivity {

/**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a
 * {@link FragmentPagerAdapter} derivative, which will keep every
 * loaded fragment in memory. If this becomes too memory intensive, it
 * may be best to switch to a
 * {@link android.support.v4.app.FragmentStatePagerAdapter}.
 */
private SectionsPagerAdapter mSectionsPagerAdapter;

/**
 * The {@link ViewPager} that will host the section contents.
 */
private ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(mViewPager);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";

    public PlaceholderFragment() {
    }

    static WebView mWebView;

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */
    public static PlaceholderFragment newInstance(int sectionNumber) {
        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        mWebView = (WebView) rootView.findViewById(R.id.webview);

        // Enable Javascript
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);

        // Force links and redirects to open in the WebView instead of in a browser
        mWebView.setWebViewClient(new WebViewClient());

        return rootView;
    }

    public static void loadURL (String url) {
        mWebView.loadUrl(url);
    }

}

/**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                PlaceholderFragment.loadURL("https://www.google.com");
                return PlaceholderFragment.newInstance(position + 1);
            case 1:
                PlaceholderFragment.loadURL("https://m.facebook.com");
                return PlaceholderFragment.newInstance(position + 2);
            default:
                PlaceholderFragment.loadURL("https://m.facebook.com");
                return PlaceholderFragment.newInstance(position + 3);
        }
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return "SECTION 1";
            case 1:
                return "SECTION 2";
            case 2:
                return "SECTION 3";
        }
        return null;
    }
}

}

错误：

FATAL EXCEPTION: main
                                               Process: tabbed.zeerooo.com.tabbed, PID: 12855
                                               java.lang.NullPointerException: Attempt to invoke virtual method 'void android.webkit.WebView.loadUrl(java.lang.String)' on a null object reference
                                                   at tabbed.zeerooo.com.tabbed.MainActivity$PlaceholderFragment.loadURL(MainActivity.java:138)
                                                   at tabbed.zeerooo.com.tabbed.MainActivity$SectionsPagerAdapter.getItem(MainActivity.java:157)
                                                   at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:101)
                                                   at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:1034)
                                                   at android.support.v4.view.ViewPager.populate(ViewPager.java:1182)
                                                   at android.support.v4.view.ViewPager.populate(ViewPager.java:1116)
                                                   at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1642)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5537)
                                                   at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:714)
                                                   at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:90)
                                                   at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1375)
                                                   at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:784)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5537)
                                                   at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
                                                   at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5537)
                                                   at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                   at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                   at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5537)
                                                   at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5537)
                                                   at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
                                                   at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
                                                   at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5537)
                                                   at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
                                                   at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2615)
                                                   at android.view.View.measure(View.java:17565)
                                                   at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2045)
                                                   at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1196)
                                                   at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1409)
                                                   at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1084)
                                                   at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5990)
                                                   at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
                                                   at android.view.Choreographer.doCallbacks(Choreographer.java:580)
                                                   at android.view.Choreographer.doFrame(Choreographer.java:550)
                                                   at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
                                                   at android.os.Handler.handleCallback(Handler.java:739)
                                                   at android.os.Handler.dispatchMessage(Handler.java:95)
                                                   at android.os.Looper.loop(Looper.java:135)
                                                   at android.app.ActivityThread.main(ActivityThread.java:5343)
                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                   at java.lang.reflect.Method.invoke(Method.java:372)
                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)

Answer 1

您可以使用片段创建应用。这个片段将有WebView，它将接受一个参数“URL”并显示它。

不，问题是如何？

只需创建一个活动和一个片段。创建TabLayout 和ViewPager 并通过扩展FragmentPagerAdapter 创建一个适配器。创建选项卡的新实例并将其添加到活动中的适配器。

在这里，您必须向片段的每个实例发送一个参数“URL”。